The present invention relates to a speaker system which is used for video equipment, such as a TV and audio equipment for automobile and a TV utilizing the speaker system.
A method for providing a horn or an acoustic pipe in the front of a speaker to introduce sound wave generated by the speaker to an opening of the horn or the acoustic pipe has been widely used since it has advantages by which large sound pressure can be obtained and sound can be transferred in a specific direction in comparision with a case in which no horn or acoustic pipe is used. A prior art speaker system with an acoustic pipe will be described with reference to FIGS. 13 to 17.
FIG. 13 is a plan view illustrating a TV with a pair of middle and low frequency range speaker systems which comprise the prior art speaker systems in which acoustic pipes are used. The speaker systems are incorporated into the TV to be located along a cathode tube 4. Each of the speaker systems includes a middle and low frequency range reproducing speaker 1 and an acoustic pipe 2 disposed in front thereof for conducting sound wave. A TV cabinet 3 of the TV is formed to fit to the speaker systems for miniaturizing the TV in size.
FIG. 14 is an exploded perspective view showing the construction of the prior art speaker system of FIG. 13. In FIG. 14, reference numeral 5 designates an acoustic equalizer provided at an front portion of the middle and low frequency range reproducing speaker 1. On the opposite sides of the acoustic equalizer 5 there are formed a pair of apertures 7 for conducting sound wave emitted from the middle and low frequency range reproducing speaker 1 into the acoustic pipe 2. Reflection plates 6 are provided outside the apertures 7. A sound absorbing material 9 is placed on both sides of the reflection plates 6. Each of the acoustic pipes 2 includes a panel 8 and a cover 10 covering an upper open side thereof.
The acoustic equalizer 5 and the reflection plates 6 which are provided in the front of each of the speakers 1 serve to improve high frequency characteristic of the speaker system. The sound absorbing material 9 placed outside the vertical reflection plate 6 serves to suppress a standing wave which is produced within the acoustic pipe 2. Each of the acoustic pipe 2 is formed so that the cross-sectional area thereof is gradually increased from the front portion of the middle and low frequency range reproducing speaker 1 toward the open end of the acoustic pipe.
FIGS. 15 and 16 are perspective views showing conventional TVs each utilizing middle and low frequency range reproducing speaker systems with acoustic pipes 2 above described and high frequency range reproducing speakers. In FIG. 15, reference numeral 11 designates an open end of the acoustic pipe of each of the middle and low frequency range reproducing speaker systems, and 12 indicates a high frequency range reproducing speaker arranged above the open end 11. In the TV of FIG. 16, each of the high frequency range reproducing speakers 12 is arranged at the front portion of the open end 11 of the corresponding middle and low frequency range reproducing speaker system.
To make the TV compact relatively easily, the high frequency range reproducing speakers 12 are placed at the front of the TV for the following reasons: for the purpose of conducting sound to the opening end portion thereof in a manner similar to that of the middle and low frequency range reproducing speaker system using the acoustic pipe 2, it is necessary to appropriately dispose a sound absorbing material 9 within the acoustic pipe 2 to remove a standing wave generated within the acoustic pipe 2; and the inner construction of the acoustic pipe 2 becomes rather complicated to conduct a high frequency component to the front of the open end 11 without attenuation.
These construction, however, makes the middle and low frequency range reproducing speaker 1 and the high frequency range reproducing speaker 12 rather different from each other in mounted position, and the difference in phase between sound waves reproduced by the middle and low frequency range reproducing speaker 1 and the high frequency range reproducing speaker 12 is produced in every frequency band. Thus, as shown at 24 in FIG. 17, a sound pressure vs. frequency characteristic with many peak dips is thus provided to the speaker systems, and the speaker systems are also provided with an unnatural tone quality.
Furthermore, the TV having the high frequency range reproducing speaker 12 arranged above the middle and low frequency range reproducing speaker 1 as shown in FIG. 15 raises a problem in that sound moves up and down in a middle and high frequency range since the middle and low frequency range reproducing speaker 1 and the high frequency range reproducing speaker 12 are greatly different in mounted position. This deteriorates performance of the speaker systems in sound image localization and articulation of sound, and the speaker systems are not sufficient for an advanced TV.
Accordingly, it is an object of the present invention to provide a speaker system which is capable of exhibiting excellent sound characteristics in sound image localization and in articulation of sound, which cannot be provided by the prior art.